CN102322247A - Device and method for evaluating displacement capability of wetting phase of rock at high temperature under high pressure - Google Patents

Abstract

The invention relates to a device and method for evaluating the displacement ability of rock wetting phase under high temperature and high pressure. The device is mainly composed of a displacement device, a constant temperature box and a pressure pump. The replacement device is composed of a rock core chamber, a tapered channel and a measuring part. The rock core chamber is a steel cylinder, and the rock core is placed in the steel cylinder. There is a liquid inlet with a valve at the bottom of the rock core chamber, and the liquid inlet is connected to the The pressure pump outside the constant temperature box is connected. The measuring part is composed of a thick-walled glass tube with scale and a steel sleeve with holes outside the glass tube. The core chamber and the measuring part are connected through a tapered channel. The invention is reliable in principle, easy to operate and strong in practicability. It can not only simulate the real reservoir environment of underground high temperature and high pressure, but also realize the rapid removal of oil from the core surface and accurately read the oil output. It is a wetting phase under high temperature and high pressure environment. The displacement efficiency provides an effective evaluation method, and provides a reliable basis for guiding the site to design a reasonable injection-production scheme.

Description

A device and method for evaluating the displacement capacity of rock wetting phase under high temperature and high pressure

technical field

The invention relates to the field of petroleum industry, an experimental device and method for evaluating the ability of a core wetting phase to displace a non-wetting phase in a high temperature and high pressure environment during oil and gas field development.

Background technique

The wetting phase displacing the non-wetting phase describes the mass transfer phenomenon between the fracture and the matrix. The wetting phase, as a displacement force, is the main oil displacement mechanism in the water injection development process. The displacement capacity of the wetting phase is low. The production of crude oil is determined in the development of permeable tight fractured reservoirs (water is the wetting phase and oil is the non-wetting phase). However, in the actual oilfield water injection development process, there is no way to know what water injection volume and water injection speed can achieve the most efficient oil and gas recovery. Therefore, laboratory experiments to analyze and evaluate the displacement capacity of wetting phase are of great significance to guide the design of reasonable water injection development schemes and enhance the ultimate recovery in mines.

At present, the industry mainly calculates the displacement efficiency by placing the oil-saturated core into a device equipped with water injection under normal temperature and pressure, and monitoring the amount of oil displaced by water displacement. This experimental method has obvious defects:

(1) The existing experimental methods for evaluating the displacement capacity of wetting phases are mainly aimed at normal temperature and pressure environments, without considering the influence of temperature and pressure effects on the displacement efficiency of wetting phases, that is, they cannot simulate the real underground reservoir environment.

(2) In order to meet the visualization requirements of the existing experimental device, the material of the device is made of glass, but the glass material cannot withstand excessive pressure.

(3) The traditional experiment takes too long, because the precipitated oil adheres to the surface of the core and is difficult to detach, so the deoiling can only be achieved by a vibration device, which will inevitably lead to experimental errors.

Contents of the invention

The purpose of the present invention is to provide a device for evaluating the wetting phase displacement ability of rocks under high temperature and high pressure. The device can not only simulate the real reservoir environment of underground high temperature and high pressure, but also allow oil to quickly leave the core surface to ensure that the experimental data is accurate and reliable. , which provides an effective evaluation method for the wetting phase displacement capacity of rocks under high temperature and high pressure conditions.

Another object of the present invention is to provide a method for evaluating the wetting phase displacement capability of rocks under high temperature and high pressure using the device. The method is reliable in principle, easy to operate, strong in practicability, and has broad market application prospects.

In order to achieve the above technical objectives, the present invention provides the following technical solutions.

A device for evaluating the displacement ability of rock wetting phase under high temperature and high pressure, mainly composed of a displacement device, a constant temperature box and a pressure pump. The displacement device is located in the constant temperature box. The displacement device is composed of three parts: the following is The core chamber where the core is placed has a measuring part on the top and a tapered channel in the middle. The core chamber is a steel cylinder made of stainless steel, the core is placed in the steel cylinder, and the space between the core and the steel cylinder is used to simulate the fracture in the formation relative to the matrix; there is a liquid inlet with a valve at the bottom of the core chamber , the liquid inlet is connected to the pressure pump outside the constant temperature box, and the external pressure pump is used to inject water into the above-mentioned simulated fractures to achieve pressurization. After the experiment, the pressure is relieved through the pressure pump, and the pressure relief gives the core chamber a pressure. During the activation process, the oil attached to the surface of the core will quickly leave the surface of the core and enter the measurement part through the tapered channel; the measurement part is composed of a thick-walled glass tube with a scale, and the outside of the thick-walled glass tube is supported by a steel sleeve. The steel sleeve has holes. On the one hand, it can fix and strengthen the glass tube and improve the pressure bearing capacity of the glass tube. On the other hand, it provides a visual window for reading values; there is a steel tapered channel in the middle of the core chamber and the measurement part. On the one hand, its function is to allow the displaced oil to enter the measuring part conveniently and quickly; on the other hand, it realizes the connection of the upper and lower parts and facilitates the disassembly of the whole device. The pressure pump is equipped with a pressure gauge to monitor the internal pressure of the core chamber in real time during the whole experiment. The thermostat can realize temperature control, and the displacement device and the pressure pump located in the thermostat are connected through pipelines.

The displacement ability of wetting phase is affected by many factors. To study the weight of these influencing factors, it is first necessary to conduct experimental research in the formation environment of high temperature and high pressure. The device provided by the invention can realize the simulation of real reservoir environment , but also to monitor the influence of pressure and temperature effects on the displacement capacity of the wetted phase. The cores used in the experiment should be pretreated by salt washing, oil washing, drying, etc. before the experiment, and the pretreated cores should be saturated with oil. The device is placed in a constant temperature box to achieve temperature control, and a pressure pump is used to inject water into the core chamber to achieve pressurization and pressure control. Due to the dynamic action of the wetting phase, the water will displace the oil inside the core. When the oil is displaced into the "fracture", due to the density difference between water and oil, the oil will be under the action of gravity and the pressure excitation process caused by pressure relief. It will quickly float up into the glass tube of the measuring part of the displacement device to realize the reading of the oil output. The pressure and pressurization period can be adjusted through the external pressure pump, and the experimental temperature can be adjusted through the thermostat. Record the oil output volume under different conditions, and the displacement oil recovery efficiency can be calculated by formula (1) (2):

$\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="m"\; filenames="HDA0000069140360000011.png"\; state="\{\{state\}\}">m</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

η-Recovery factor (%)

M ₁ , M ₂ - mass of core before and after oil saturation (g)

V ₁ , V ₂ - fully oil-saturated volume of core and oil-flowing volume of core (cm ³ )

ρ-the density of the oil used in the experiment (g/cm ³ )

In the formula, M ₁ and M ₂ are obtained by weighing with a precision electronic balance, V ₁ is an indirect quantity obtained by calculation, V ₂ is obtained by reading from a displacement device, and ρ is a constant.

With the support of the above experimental devices and methods, the evaluation of the wetting phase displacement capability under high temperature and high pressure conditions can be realized.

A method for evaluating the displacement ability of rock wetting phase under high temperature and high pressure, which includes the following steps in sequence:

(1) Saturate the core with oil, and weigh the core before and after oil saturation to obtain M ₁ and M ₂ , and calculate V ₁ using the following formula:

${\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="m"\; filenames="HDA0000069140360000011.png"\; state="\{\{state\}\}">m</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}<span\; class="notranslate">\; ;</span>$

(2) Put the oil-saturated core into the center of the core chamber of the displacement device, put the displacement device in a constant temperature box, adjust to the required temperature, and at the same time inject water into the core chamber through the pressure pump to make the core completely soaked in water;

(3) Continue to inject water to raise the pressure to the pressure required by the experimental design, and start the displacement experiment;

(4) Read the oil volume V ₂ through the graduated thick-walled glass tube in the measuring part of the displacement device, and use the following formula to calculate the displacement efficiency η of the wetting phase:

$\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="V"\; filenames="HDA0000069140360000011.png"\; state="\{\{state\}\}">V</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; ;</span>$

(5) Steps (2), (3), and (4) are repeated until the displacement is completed, so as to realize the evaluation of the displacement capacity of the wetted phase at different pressures and temperatures.

When starting the displacement test, the device is tested first, and the pressure pump is used to inject water into the displacement device to suppress the pressure. If the pressure drops after a few minutes, it means that the device is not airtight. Check whether there is any water leakage. If the pressure remains constant, the device is good.

In order to let the oil leave the core surface quickly, a layer of wetting reversal agent is applied to the inner surface of the core chamber and the tapered channel to make the inner surface of the steel cylinder hydrophilic, so as to prevent the precipitated oil from adhering to the surface and not all entering the measurement part.

In order to further ensure the accuracy and reliability of the experimental data, the core should be subjected to pretreatments such as salt washing, oil washing, and drying before being saturated with oil.

Compared with the prior art, the measuring method and device provided by the present invention are reliable in principle, simple in structure and strong in operability, and its beneficial effects are:

(1) It can simulate the real reservoir environment of underground high temperature and high pressure to ensure the authenticity and reliability of the experimental conditions;

(2) It can conveniently adjust the experimental temperature and pressure, and monitor the influence of temperature and pressure changes on the wetting phase displacement capacity;

(3) The oil precipitated after the traditional experiment will adhere to the core surface and affect the reading value of the oil output. The present invention realizes that the oil is quickly separated from the core surface and the oil output can be accurately read.

Therefore, the present invention provides an effective evaluation method for evaluating the displacement efficiency of the wetting phase in the high-temperature and high-pressure real reservoir environment, and provides a reliable basis for guiding the field to design a reasonable injection-production scheme.

Description of drawings

Figure 1 is a schematic diagram of the structure of a traditional displacement measurement device.

Fig. 2 is a structural schematic diagram of the device for evaluating the displacement capacity of rock wetting phase under high temperature and high pressure according to the present invention.

Fig. 3 is a schematic structural diagram of the displacement device in Fig. 2 .

In the figure: 1 glass cover; 2 glass water tank; 3 rock core; 4 pressure pump; 5 connecting pipeline; 6 displacement device; 7 constant temperature box; 8 valve; Thick-walled glass tube; 13 steel sleeves with holes.

Detailed ways

Further illustrate the present invention below in conjunction with accompanying drawing.

see picture 1. Fig. 1 is a traditional displacement measuring device. The simulated injection water is placed in a glass tank 2; the core 3 is placed in the center of the tank so that the core is completely immersed in the simulated water environment; the glass cover 1 is placed in the tank Surround the core, and then start the water flooding experiment, and the precipitated oil will automatically enter the upper part of the glass cover under the action of gravity, so as to record the amount of oil produced.

See Figure 2 and Figure 3.

A device for evaluating the displacement ability of rock wetting phase under high temperature and high pressure, mainly composed of a displacement device 6, a constant temperature box 7 and a pressure pump 4, the displacement device is located in the temperature control box, and the displacement device is placed The rock core 3 consists of a core chamber 9, a tapered passage 11 and a measuring section. The rock core chamber is a steel cylinder, the rock core is placed in the steel cylinder, and the space between the rock core and the steel cylinder is used to simulate formation fractures. There is a liquid inlet with a valve 8 at the bottom of the core chamber, and the liquid inlet is connected with the pressure pump 4 outside the constant temperature box through the connecting pipeline 5. The measuring part is composed of a thick-walled glass tube 12 with a scale and a glass tube outside the glass tube. The perforated steel sleeve 13 is composed, and the core chamber 9 and the measurement part are connected through a tapered channel 11 .

Before starting the test, first check whether the displacement device (see Figure 3) is airtight, and inject water into the core chamber through the liquid inlet valve 8 to suppress the pressure to 1MPa. After 2 minutes, see that the pressure gauge on the pressure pump does not change, indicating airtightness Good, otherwise, recheck the test until the pressure does not drop; apply a layer of wetting reversal agent on the inner surface of the core chamber and the tapered channel to make the inner surface of the steel cylinder hydrophilic, and prevent the precipitated oil from adhering to its surface and not all Enter the measurement department; use a standard core with a length of 50 mm and a diameter of 25 mm for salt washing, oil washing, drying, weighing and oil-saturated pretreatment; wipe the surface oil of the pre-treated core with a clean towel and weigh it After weighing, put it into the central position of the core chamber 9 of the displacing device whose airtightness is intact after inspection and tighten the device; put the displacing device that has been debugged into a constant temperature box with a temperature of 60°, and pass through the external pressure pump 4 to Inject the simulated injection water 10 into the hollow part between the core and the steel cylinder in the core chamber, so that the core is completely immersed in the injection water; continue to inject water through the pressure pump to raise the pressure to the experimental requirements (1MPa, 2MPa, 3MPa, 5MPa), and start Displacement experiment: After pressurizing for 5 hours, use the valve connected to the core chamber to release the pressure. During this process, the oil spontaneously enters the visualization part of the measurement part. When the pressure drops to normal pressure, let the device stand still for 1 hour, and pass The upper part of the displacement device can read the oil output through the thick-walled glass tube with scale, so as to calculate the displacement efficiency and realize the evaluation of the displacement capacity of the wetting phase.

Claims (2)

1. A device for evaluating the displacement capacity of rock wetting phase under high temperature and high pressure, mainly composed of a displacement device (6), a constant temperature box (7) and a pressure pump (4), it is characterized in that the displacement device is located at In the temperature control box, the displacement device is composed of a core chamber (9), a tapered channel (11) and a measuring section, the core chamber is a steel cylinder, the core (3) is placed in the steel cylinder, and the core The space between the steel cylinder and the steel cylinder is used to simulate formation fractures. There is a liquid inlet with a valve (8) at the bottom of the core chamber, and the liquid inlet is connected with the pressure pump (4) outside the constant temperature box. The measuring part It consists of a graduated thick-walled glass tube (12) and a steel sleeve with holes (13) outside the glass tube. The rock core chamber (9) and the measuring part are connected through a tapered channel (11). 2. utilize the method for the device evaluation described in claim 1 rock wetting phase to displace ability under high temperature and pressure, comprise the following steps successively: (1) Saturate the core with oil, weigh the core before and after the oil saturation, and calculate V ₁ using the following formula: ${\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}$ Among them, M ₁ , M ₂ ——mass (g) of the core before and after oil saturation, ρ——the density of the oil used in the experiment (g/cm ³ ); (2) Put the oil-saturated core into the center of the core chamber of the displacement device, put the displacement device in a constant temperature box, adjust to the required temperature, and at the same time inject water into the core chamber through the pressure pump to make the core completely soaked in water; (3) Continue to inject water to raise the pressure to the pressure required by the experimental design, and start the displacement experiment; (4) Read the oil volume V ₂ (cm ³ ) through the graduated thick-walled glass tube in the measuring part of the displacement device, and use the following formula to calculate the displacement efficiency η of the wetting phase: $\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; ;</span>$ (5) Steps (2), (3), and (4) are repeated until the displacement is completed, so as to realize the evaluation of the displacement ability of the wetted phase at different pressures and temperatures.

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